Persistent identifier
From Science Europe Data Glossary
Definition: a persistent identifier is a long-lasting reference to a digital object — a single file or set of files.
Explanation: several alternative persistent identifier systems exist, such as: Digital Object Identifiers (DOIs), Persistent Uniform Resource Locators (PURLs) and Uniform Resource Names (URNs).
Reference: https://en.wikipedia.org/wiki/Persistent_identifier